CA2204056C - Polymerization apparatus - Google Patents

Abstract

A polymerization apparatus includes a first chamber and a second chamber and a flexible, radioparent diaphragm separating the first chamber from the second chamber. A radiation source emitting polymerization-inducing radiation into the first chamber is provided. The second chamber is adapted for receiving a model and a foil, positioned between the diaphragm and the model, to be subjected to the radiation of the radiation source. A device for generating a pressure differential between the first and the second chamber for deflecting the diaphragm toward the model to thereby deform the foil at the model is provided. An adjusting device for adjusting the distance between the model and the diaphragm is provided.

Description

CA 022040~6 1997-04-30 POLYMERIZATION APPARATUS
Background of the Invention The present invention relates to a poly. "~r ' . ~ apparatus includins a radiation source for emitting radiation for inducing pol~"eli ~ n, especially radiation in the form of light, into a Sirst chamber, ov"l~.ri~ing a flexible radiopal~"~ men~l,ld,le or diaphragm that separates the second chamber from a hrst chamber, whereby into the second chamber a model to be subjected to radiation is placed, especial~ a tooth ~stump, and whereby between the model and the membrane a foil is provided.
The membrane, with the aid of a differential pressure, is deflected into the seGond chamber toward the model in order to deform the foil about the model.
Such a pol"" ,el i~ apparatus is known from ~ r,ldti~nal Patent ApplicaUon WO 95/08300. In this poly,l,ali " ~ apparatus a piece of pre-i",pl~y~dl~ matrix material is placed onto a tooth stump or another model The term model in the context of the present invention refers to pos'~tive molds as well as negative molds.
Due to the dfflerential pressure between the two chambers in the apparatus, a soft and flexible diaphragrn posltioned in the CA 022040~6 1997-04-30 apparatus is forced onto the model (mold) so that the foil is pressed onto the model and is shaped according to the contour of the model.
A problem of such F51~ apparatus is ensuring a precise and reliable pol~ne,i " .) by light curing. Especially in the case of dental, e~lac~, . ,e"I parts, it is imperative that complete curing takes place whereby complete curing must be ênsured within a limited amount of time. Thus, in general, output-intensive light sources (high luminous power~ with cvlle~"onvi"g spectra are used. For thermal as well as energetic reasons, the light electrical power usage should not be too great especially since high light intensity light sources are C~ d~d~;v~ly expensive to replace on a regular basis when spent.
I n the apparatus known from the dro~ t;oned r r ~
the light radiation must penetrate the flexible diaphragm and this results in certain losses of luminous power. Furthemmore, the distance bet~veen the tooth stump and the light source must be selected such that for ail model sizes occurring in practice sufficient space is provided. On the other hand, the luminous power is reduced more than p, v~,o, ~iOI ,a:l~ wlth increasing distanoe so that measures for increasing luminous power have become known.

CA 022040~6 1997-04-30 These measures include, for example, the teaching disclosed but not discussed in detail in the dr~l~"~" .,ed p~ . For improving the reflection of light beams within the area of the radiation source special reflectors in the form of an annular mirror 19 that fills the entire model chamber are provided.
The cycle times for the actual light curing process is d~t~l "~ ed substantially by how fast the required vacuum can b~
generated within the model chamber For the d~ful~ of the foil which must adhere to the contour of the model, the , " ~ of a uniform high force is required which in practice is realized by a co, le~JOr,Ji"y pressure " l' This pressure differential in cù~ eC~iu,~ with partly rugged or fissured rrlodels result in a ~,vl~idt:~aul~ stress load of the flexible diaphragm. The diaphragm must therefore be e~ "yed quite frequently for safety reasons because a sm~ll hole or crack wlthin the diaphragm would have di~ad~/dll~d~écus results in regard to the molding process.
It is therefore an object of the present invention to provide apo~."e:,i,d~i.,"apparatusofthe~f~,len~"~;u"e~kindwithwhich the light output as well as the service life of the diaphragm can be improved.

CA 022040~6 1997-04-30 Surnmary of the inYention A poly" ,e~ ", apparatus according to the present invention i5 primarily ~ llclac~ d by:
A first chamber and a second chamber;
A flexible, r~diopa, ~:"I diaphragrn separa~ing the first chamber from the second chamber;
Aradiationsourceemiffingpolyl"~ cG~"-inducingradiation into the fin;t chamber;
The second chamber adapted for receiving a model and a foil, positioned between the diaphragm and the model, to be subjected to the radiation of the radiation source;
A device for generating a pressure differential between the first and the second chamber for deflecting the diaphragm toward the model to thereby deform the foil about the model;
An adjusting device for adjusting a distance between the model and the diaphragm.
The second chamber has a support deYice for the model, wherein a height of the support deYice and a distance to the diaphragm is a~ Ahle.
The support device preferably comprises a support plate and an tA.,I,c."y~:aLle support insert for supporting the support -4- , CA 022040~6 1997-04-30 plate.
The support insert is a spacer ring.
The second chamber comprises pressure-stable filling bodies positioned external to the area in which the model and the foil are located and external to the area bet~veen the dia,u~lld and the foil.
The device for generating a pressure differential includes an air supply connected to the first chamber for introducing air to create the pressure differential in the form of a greater pressure in the first chamber than in the second chamber.
The device for generating a pressure differential includes a first vacuum source connected to the first chamber and a second vacuum source connected to the second chamber, the first and second Yacuum sources adapted to produce a vacuum relative to the dllllUSpl~ surrounding the poly,,,eri~dG~I~ apparatus.
The first chamber comprises a cover and the radiation source is positioned a50ve the cover of the first chamber, wherein the cover comprises a radio~.a,~:"l pane.
The pol~ d~ , apparatus further comprises an infrared filter positioned bet~veen the radiation source ard the first chamber.

CA 022040~6 1997-04-30 Preferably, the second chamber comprises a closure device ~or pressure-tightly closing the second chamber.
AdYd,~ta3~ously, the pol~"~riLd~;on apparatus Comprises a flrst part and a second part ~ ably connected to one another, wherein the first part includes the first chamber and the ~ia~ ra~
and the second part includes the second chamber. I
The poly,.,er t :n apparatus also includes a closure device, wherein the first part is a top part including the radiation source and the second part is a boffom part, wherein the first part and the second part are connected to one another by the closure device.
The closure device is preferably a bayonet closure.
Preferably, the support device comprises a pedestal extending upwardly into the seoond chamber and receiving at least one of the models centrally within the second chamber.
The radiation source includes a plurality of individual lights arranged adjacent to one another.
A~a~layeouslyl the individual lights are focused on an area in which the model is p - r, 1.
Expediently, the individual lights are arranged at an obtuse angle to one another and have an optical axis i"t~r~F:ig one ~6-CA 022040~6 1997-04-30 another in the area in which the model is positioned.
Surprisingly with the inventive height ~dj~ y a plurality of advd,~tdges can be achieved. The diaphragm must not be as v~f:~v~ le as in the prior art sO that its stre~s load is greatly reduced and its service life is greatly improved. The eli.,.il,aliol~
of me annular mirror also allows in practice that the model with the foil can be brought cioser to the diaphragm. Thus, the distance to the fadiation source or light sources can be reduced so that the luminous power is improved. It is understood that, if desired. the entire intefior of the po:,~, . ,eri~lion apparatus can be provided with reflective svurfaces.
The minimally required deflection of the diaphragm is also favorable in regard h light-t~vl)f~ol~yiv~ ide,t,liol ,s. It can be made of thin material with better light l,a"~",i,,iYity without reducing its service life.
According to an ad~dllldy~:o,ls e",!v.,di",el~l it iS suggested that filling bodies are positioned laterally to the pedestal of the model. T filling bodies are provided with reflective surfaces. With the inventive e,,,Lov!i,,,~ ,t the time required for applying the pressure dif~erential (to apply a greater pressure to the first chamber as compared to the se~ond chamber) can be greatly CA 022040~6 1997-04-30 reduced because a colls;de,dl,le number of filling bodies can be proYided which are pressure-stable so that the model chambêr thus has a reduced amount of air space that must be evacuated.
This also results in a c~r":s~on~il,g'~ reduced operating time and/or output requirement for the vacuum pump.
According to an especially dd~dl l~d~eous ~ b~ lerlt, it is suggested h operate the apparatus with a single pump that removes air from the model chamber into the ~"",,~,si~n chamber i.e., guides air from the second chamber into the first chamber. This allows for an especially effective operation, and an additional vacuum pump can be eliminated.
According to a hrther preferred ~" ,~odi" lel ~, it is suggested to provide the height ~dj~ by employing inserts. The adjusting device, for example, can be in the form of a spacer sleeve that is excl~dnyêc.blc: and can be placed under the support plate for the models. The inserts can also be embodied as a filling body and can thus reduce the space to be evacuated.
According to another especially preferred ~Inb~ llel It, it is suggested to realize the adjusting device fot the inventive height adjustrnent by providing snap-on positioning elements provided at the circumferential inner wall of the model chamber. They allow - 8 ~ I

for a spring-loaded snapping of the support plate into the inner wall. The support plate is provided at its periphery with spring-loaded balls that are positioned at locations matGhing the locations wlthin the inner walls so that after surpassing the snap-on force a movement of the support plate in the downward or upward direGtion is possible.
According to another ~dvdn~geous ~" ,bocli" ,~r,t, it is suggested that the inventive adjusting dev;ce comprises a support " ,e~,l ,al~is~n for the support plate that allows vertical d;SpldG~
Vvith a pressure-tight force ~, di 'sn~ ." device extending into the apparatus, the height adjustment can be actuated from the exterior so that a height adjustment can be performed even after closing the pc,ly-,~eli~d~ioll apparatus.
The pressure-tight force ~ "~",i,,io" device can, for example, be realized by an axle which penetrates the model chamber wall so that a pivot bearing for the hei3ht adjustment is possible. In order to maintain the support plate in a horizontal position this ~" ,l-v-li" ,~ preferabry includes a pd,~tuy, ~.h guiding ",ee1,al,is,~ ", guide) for the support plate.
According to a further preferred ~ odi~ of the adjusting device, It is sugge~ert that the adjus~ing device is CA 022040~6 1997-04-30 .
operated with a drive motor, especially an electric motor, posltioned within the model chamber. For example, small electric motors can be flanged to the boltom of the support plate which are provided with pinions that mesh with toothed racks positioned at the inner wall of the model chamber. It is understood that the thus fommed gear system should be embodied so as not to require lubrication and should, for example, be comprised of plastic in order to prevent contd" ,i, .~.t~,n of the foil to be polymerized in the vacuum in the chamber.
Brief Description of the Drawings The object and ~d~dl~ldue:s of the present invention will appear more clearly from the following spe~ ~';A?~:ol~ in conjunction with the a~v""~)a");.,g drawings, in which:
Fig. 1 is a first ~",~o.l;",e"t of the inventive po!~."e,~i~dliui, apparatus;
Fig 2 is a second ~",bo~i",elll of the inventive puly.,.~ri~dliu,, apparatus;
Fig. 3 is a plan view of the bottom part with removed top part of a further ~ udi~ l of the inventive pol~",e~ apparatus; and Fig. 4 is a schematic side view of the e"lL~li",ellt CA 022040;i6 19~7-04-30 of Fig. 3.
Description of Pteferred Ei"lodi,n~:"~
The present invention will now be described in detail with the aid of several specif c t:, . ,bodi" .e n~ utilizing Figures 1 through 4.
The ~ bGJil~ t ~ ser~t~ in Fig. 1 of a poly~ iùn device 10 comprises a bottom part 12 and a top part 14. The top part 14 is d~L~ aL~ly connected to the bottom part 12 for which purpose a bayonet closure 16 is provided. The top part 14 comprises a radiation source 18 with two lights 20 and 22 that emit radiation within the spectrum of visible light optionally v~ith a minimal UV light portion. It is understood that instead of the lights 20 and 22 other radiation deYices suitable for light curing can be used. The lights 20 and 22 are arranged so as h be slightly slanted so that they focus on an area slightly below the end of the top part 14. They are cooled with a non~ pr~ .,t~d blower and are supported just above a first chamber (co"~p~iun chamber) 24 of the top part 14. The c~".p,~;,ion chamber 24 comprises a cover 26 that is ,adiopale,~t for the radiation emitted by the radiation source 18. An annular wall 28 extends in a circular fashion about the c~,.,pl~s~;ol1 ~h~mber 24. Bet~veen the CA 022040~6 l997-04-30 radiation source 18 and the cover 26 an infrared filter 27 is provided in order to reduce the heat loading of the poly.nc, i~li apparatus 10.
The w, ",ur~:ssiDn chamber 24 is closed off in the downward direction by a diaphragm 30 that is flexible and ~xpar,ddble. It is clamped at its outer circumference with beads 32 in the annulat wall 28. The top part 14 comprises furthermore a protective cover 34 which covers the entire height of the top part 14.
The annular wall 28 has a pressure connector ~air supply), not ~ csc"~cd in ri9. 1, with which the c~ ~ ", ~sion chamber 24 can be pressurized. For this purpose a non-l~ple~e,,lcd c~"",,~ss~r is provided.
The bottom part 12 comprises a second chamber (model chamber) 36 that is surrounded by pressure-tight model chamber walls 38. Within the model chamber 36 a support device 4~ is provided that serves for supporting a model 42. The model 42 can include a number of tooth stumps 44, 4O whereby ~n the shown ~ Jdillle~lll two toothed stumps are shown. A foil 48 50 ~ is posiUoned thereon. The support device 40 provides a pedesbl 52 for the tooth stumps 44 and 46. The pedestal 52 is resting on a support plate 54 whereby the space between the model chamber wall 38 and the pedestal 5Z is preferably filled with ball-shaped f lling bodies 56. The filling bodies 56 serve to reduce the free air space within the model chamber 36 as well as to support the diaphragm 30 during the molding process. The support device 40 ~ ly its pedestal may also be part of the model or its height can be adjusted for ex~mp~e by placing spacer plates underneath.
The inventive adjusting device g8 comprises in the leprese )lod ~. lb~ an e .~ a yeable spacer ring 60 which is supported on the bottom 62 of the boffom part 12. ~ts height d~t~ s the level of the SuppOn plate 54 and thus the distance between the foil 48 and the diaphragm 30. ~t is inventively suggest ~ depending on the size of the tooth stumps t: pe l: ~ly of the model to employ spacêr rings 60 of different heights so that the model is always positioned as close as possible to the diaphragm 30.
The filling bodies 56 are preferably provided with a reflective surface so that the puly eri a~iu ~-inducing radiation is reflected thereat and can reach the foils 48 50. The inner surfaces of thê annular wall 28 and of the model cham~er 36 are a~so preferably reflective which a~so increases the li~ht output or CA 022040~6 1997-04-30 luminous power.
The model chamber 36 is provided with a non-~:pr~se,)led Yacuum connector that is connected to a vacuum source (Yacuum pump) also not shown in the drawing. The vacuum connector allows to evacuate the model charnber 36 and provides for a deep drawing of the foils 48 and 50.
The deep drawing and pol~" ,el i~dt;vl . process is carried out as follows.
In a first step, while the apparatus is open, a suitabîe spacer ring for the model to be treated is selected. It is inserted and the support plate 54 is placed onto the spacer ring. The model 42 is then centrally arranged on the support plate 54 and the surrounding area is filled with reflective plastic balls 56 such that the filling is a~ru,~i,,,.~t~ly flush with the upper side of the pedestal 52.
Subsequently, foils 48, 50 are placed onto the tooth stumps 44, 46. The foils are comprised of a light-poly~"e,i~d~le plastic material having imbedded therein hberglass, With the aid of the bayonet closure 16 the top part 14 and the bottom part 12 are connected to one another so that the pvl~ . "~ dliu" apparatus ~ O
fomms a pressure-tight unlt. The first chamber 24 as well as the -CA 022040~6 l997-04-30 .
second chamber 36 are supplied with vacuum whereby the top part 14 and the bottom part 12 are forced onto one another. The beads 32 that serve as an annular seal are simultaneously cc",~ sseci and the bayonet closure 16 can be snapped into place.
Subsequently the vacuum in the first chamber 24 is replaced with pressure of dlJplvA;~ t~-ly 2 bar. At this point the lights 20, 22 can be switched on with low output in~order to be able to monltor visual~y the model 42 through a view pori in the wall. The pressure of 2 bar within the c~lnp,~tsaivn chamber 24 forces the highly flexible and ,d ii~",al~"l diaphragm 30 onto the foils 48 and 50. The foils 48, 50 are thus pressed onto the respective tooth stump 40 and 46 in order to be molded thereto.
In this state the output of the radlation source 18 is increased to maximum output and the poly "e,i t: ~ or light curing of the foil Is carried out whiie full pressure is present within the col~l~JIe~sio chamber 24.
After c~ ti~l l of po~y~ l lel i~dt~ the pressure is reieased from the G~ chamber 24 and the cu" ,pl~:~siOI, chamber 24 is Indil~tdil~ed at normal pressure (at~"~sp~ ; pressure) or is optionally under slight vacuum. In this state the bayonet closure CA 022040;i6 1997-04-30 can be opened and the vacuum within the model chamber 36 is released.
A modified ~",bodi",~"~ of the inventive poly.~e,iLdli~l1 device 10 can be seen in Fig. 2. This apparatus is more compact than the p~ d~ apparatus according to Fig. 1. It can be supplied faster with pressure or vacuum and with less energy expenditure. The height of the comp~r~iu,1 chamber 24 is reduoed to about half in COI~ d~ to Fig. 1. In order to connect the air supply 64 a securing ring 66 of the bayonet closure 1r~ is embodied somewhat lower at the locatiorl of air supply conl~e,,l;~,n 64. Fu~ e~ .rt: the model chamber is reduced to the possible minimum size and the model 42 extends to a position in close vicinity below the diaphragm 30. The diaphragm 30 in this ~"lboJil~ thus must be flexible only to a minimal extend in cv",~,dri~on to the t"~bo.ii",~ according to Fig. 1. This is beneficial in regand to increasing its service life.
Instead of the spacer rin~ 60 a spacer body 68 is positioned below the support plate 54. The spacer body 68 fills the entire space below the support plate 54.
The spacer body 68 comprises vacuum channels 70 72 which extend over its entire height. The vacuum channels 70 72 CA 022040~6 1997-04-30 open into annular channels 74, 7~ which extend annularly about the distance body 68 at its upper side, .e~pe~tiJ~I~ underside.
With c~"~:,pol,di"y bores in the support plate 54 the introduction of vacuum via a vacuum source 78 into the upper area of the model chamber 36 is possible.
The air supply connector 64 as well as the vacuum source connector 78 are connected to non-, ~pi~ , It~d pump which, with respective switching valves, can provide vacuum to the first and second chamber as well as pressure to the first chamber.
A modif ed e" l~odi, ~ ,e"l of the adjusting deYice ~8 is shown in Figs. 3 and 4. In this e",bGdi,ll~lll the adjusting deYice 58 includes a lever 80 which is supported in a bearing bushing 82 at the model chamber wa~l 38. The lever 80 comprises a grip 84 with which the position of the support plate 54 can be adjusted from the exterior of the apparatus. The lever 80 per,~ t~3 the model chamber wall 38 a~lu,~ t~ ly tang~"tia'll to the support plate 54 and extends as a curYed portion 86 following the model chamber wall 38. ~t is of a small height in the horizontal direction.
The lever 80 comprises at the end of the curYed portion 85 a pivot joint 88 for the support plate 54. The pivot axis of the pivot joint 88 extends parallel to the axis of the bearing bushing 82 -CA 022040;i6 1997-04-30 The support plate 54 can be height-adjusted vlXh this adjusting device 58. 1 lowever, it is also desirable that it maintains Xs horizontal orientation. ~or this purpose, the pdl "~ , dlll ~ guiding ",e~,l,al,is", (pal~lvyl~vl~) 90 shown in Fig. 4 is provided which comprises two guide rods 94. As can be seen in Fig. 4, the guide rods 92 and 94 which in their projection onto their pivot axis extend parallel to one another have the same l~ngth. However, they are curved in order to extend exterior to the support plate S4.
The guide rod 92, as can be seen in Fig. 3, guides the support plate 54 oniy at one side while the guide rod 94 comprises two legs 96, 98 which surround the support plate 94 in a curved fashion. The lever 80 is supported in a slotted hole of the support plate for co",p6~ g the pivot movement of the par~ 9 a guiding Illel,llalli~l~l, as is shown in Fig. 4.
The bearing locations 100 and 102 of the guide rods 94, 92.
viewed in the Yertical direction, are posXioned d,u,ul u~ t~ :ly at the same level and à~ >lv,~ cX~ly at the level of the center of the model chamber 36. The bearing bushing 82 is also arranged at this level. With this c~vodi~c~ll it is possible to transfer the support plate 54 from the positian shown in Fig.j 4 into the lowermost posXion in which X is adjacent to the ~ottom r~2~ of the CA 022040~6 1997-04-30 bo~om part 12.
This ~ bG~ allows for a ~ast height ad~ustment w'lth the inventive adjusting device, but requires that the model chamber 36 is substantially free of filling bodies.
~ ccording to 8 further ~,,lbudi,,,el,l, it is suggested to embody the bottom 62 ûf the bottom part 12 as a pressure-tight piston that cdn be displaced by actuation from the exterior. The bottom 62 thus provides an adjusting device and it is possible to actuate this adjusting device 58, 62 from the exterior while ensuring a minimum free air space within the model chamber 36.
In a further alternative ûf this è~ o~ ,e-,l, the bottom 62 is fixedly connected to the support surface and the entlre poly",e,i~dti~r~ apparatus, exclusive of the bottom and the model placed thereon, is height-adjustable. The inventive adJusting device can also be realized by this ~ b~di~ "l.
The present invention is, of course, in no way restricted to the specific disclosure of the ~I~e~ on and drawings, but also el~Cv~ uds~es any " ~udif ~d(iOl~s within the scope of the appended clairns.

Claims (17)

1. A polymerization apparatus comprising:
a first chamber and a second chamber;
a flexible, radioparent diaphragm separating said first chamber from said second chamber;
a radiation source emitting polymerization-inducing radiation into said first chamber;
said second chamber adapted for receiving a model and a foil, positioned between said diaphragm and the model, to be subjected to the radiation of said radiation source;
a device for generating a pressure differential between said first and said second chamber for deflecting said diaphragm toward the model to thereby deform the foil about the model;
an adjusting device for adjusting a distance between the model and said diaphragm.

2. A polymerization apparatus according to claim 1, wherein said second chamber has a support device for the model, wherein a height of said support device and a distance to said diaphragm is adjustable

3. A polymerization apparatus according to claim 2, wherein said support device comprises a support plate and an exchangeable support insert for supporting said support plate.

4. A polymerization apparatus according to claim 3 wherein said support insert is a spacer ring.

5. A polymerization apparatus according to claim 1, wherein said second chamber comprises pressure-stable filling bodies positioned external to an area in which the model and the foil are located and external to an area between said diaphragm and the foil.

6. A polymerization apparatus according to claim 1, wherein said device for generating a pressure differential includes an air supply connected to said first chamber for introducing air to create said pressure differential in the form of a greater pressure in said first chamber than in said second chamber.

7. A polymerization apparatus according to claim 1, wherein said device for generating a pressure differential includes a first vacuum source connected to said first chamber and a second vacuum source connected to said second chamber, said first and second vacuum sources adapted to produce a vacuum relative to an atmosphere surrounding said polymerization apparatus.

8. A polymerization apparatus according to claim 1, wherein said first chamber comprises a cover and wherein said radiation source is positioned above said cover of said first chamber wherein said cover comprises a redioparent pane.

9. A polymerization apparatus according to claim 1 further comprising an infrared filter positioned between said radiation source and said first chamber.

10. A polymerization apparatus according to claim 1, wherein said second chamber comprises a closure device for pressure-tightly closing said second chamber.

11. A polymerization apparatus according to claim 1 comprised of a first part and a second part detachably connected to one another wherein said first part includes said first chamber and said diaphragm and said second part includes said second chamber.

12. A polymerization apparatus according to claim 11 further comprising a closure device wherein said first part is a top part including said radiation source, and wherein said second part is a bottom part, wherein said first part and said second part are connected to one another by said closure device.

13. A polymerization apparatus according to claim 12, wherein said closure device is a bayonet closure.

14. A polymerization apparatus according to claim 2, wherein said support device comprises a pedestal extending upwardly into said second chamber and receiving at least one of the models centrally within said second chamber.

15. A polymerization chamber according to claim 1, wherein said radiation source includes a plurality of individual lights arranged adjacent to one another.

16. A polymerization chamber according to claim 15, wherein said individual lights are focussed on an area in which the model is positioned.

17. A polymerization chamber according to claim 15, wherein said individual lights are arranged at an obtuse angle to one another and have an optical axis intercepting one another in the area in which the model is positioned.